1. Field of the Invention
The present invention relates to a single stage microactuator for multidimensional actuation with multi-folded springs, and more particularly, to an x-y stage microactuator for a scanning probe microscope (SPM) technique based data storage system.
2. Description of the Related Art
A scanning probe microscope (SPM) technique based data storage system includes a data storage medium, an actuator for moving the data storage medium seated on a stage in x- and y-directions, at least one probe having a tip for writing information in or reading information from the data storage medium, and a signal processor for processing an information signal.
Multiple probes can write or read one or more information signals at the same time. For information signal writing or reading, a tip of each probe should be positioned close to a medium. Thus, each of the multiple probes needs an actuator and sensor. The actuator serves to move the probe such that the tip is close to the medium. The sensor reads information from the medium by sensing actuation of the probe according to the information.
For biaxial or multidimensional actuation, for example, in x- and y-directions, at least three electrodes are required for an actuator for single-axial single-directional actuation and at least five electrodes are required for signal-axial bidirectional actuation. According to U.S. Pat. No. 5,536,988, an actuator having multiple electrodes for multidimensional motion is formed in a single silicon structure by insulation utilizing thermal oxidation of selected regions of the device. This method can resolve electrode related problems occurring in multidimensional actuation, but needs complicated processes.
Meanwhile, in an article presented by P.F. Intermuehle et al., xe2x80x9cDesign and Fabrication of an Overhanging xy-miroactuator with Integrated Tip for Scanning Surface Profilingxe2x80x9d, Sensors and Actuators A. 43 (1994) 346-350, the use of one electrode for biaxial motion is disclosed. This method is simple because there is no need for an insulation process, but a coupling problem occurs in biaxial actuating because of the structure of an actuator using one electrode.
Furthermore, this structure cannot be directly applied to a large stage for storage devices due to structural instability (easy rotational motion around the vertical axis to an actuating plane) and usable region inefficiency of the stage with respect to the dimension of the microactuctor (space lost by the length of spring between the stage and actuator).
To solve the above-described problems, it is a first object of the present invention to provide a single stage microactuator for multidimensional actuation with multi-folded springs, which utilizes one electrode for multidimensional motion, and thus the manufacturing process is simplified without a need for an insulation process.
It is a second object of the present invention to provide a single stage microactuator for multidimensional actuation with multi-folded springs, in which coupling of motions in the x- and y-directions can be effectively suppressed.
It is a third object of the present invention to provide a single stage microactuator for multidimensional actuation with multi-folded springs, in which any motion excluding motion in the x- and y-directions is effectively suppressed.
It is a fourth object of the present invention to provide a multidimensional single stage microactuator with multi-folded springs, in which a stage can be enlarged by an effective arrangement structure and thus the microactuator can be applied to actuate a large, high-density storage device.
To achieve the first object of the present invention, there is provided a single stage microactuator for multidimensional actuation, comprising: a substrate; a fixed plate electrode formed at the center of the substrate; a rectangular stage having first and second sides which are perpendicular to each other, the rectangular stage being located above the fixed plate electrode; a plurality of drive frame parts arranged close to each of the first and second sides of the stage, each of the drive frame parts having a plurality of drive frames parallel to one another and perpendicular to the sides of the rectangular stage; first spring parts each for connecting the first and second sides of the stages and the drive frame parts, each of the first spring parts having a plurality of spring members extending parallel to the first and second sides of the stage and a plurality of spring holding members for holding the spring members; a plurality of fixed frame parts arranged on each of the first and second sides of the stage, each of the fixed frame parts having a plurality of parallel fixed frames alternately arranged with the drive frames of the drive frame parts; drive comb electrodes extending parallel to one another and parallel to the first or second sides of the stage, from the drive frames of each of the drive frame parts; fixed comb electrodes extending parallel to one another from the fixed frames of each of the fixed frame parts and being interdigitated with the drive comb electrodes; and second spring parts each for supporting the drive frame parts with respect to the substrate and urging the drive frame parts in the direction of the drive comb electrodes by its elastic bias, each of the second spring parts having a plurality of spring members extending parallel to the drive frames of the drive frame parts and a plurality of spring holding members for holding the spring members.
It is preferable that the drive frames of each of the drive frame parts are connected by auxiliary drive frames at right angles to form a rectangular lattice structure. The fixed frames of each of the fixed frame parts may be fixed to the substrate and may bee separately and electrically connected for each of the fixed frame parts.
It is preferable that each of the fixed frames of the fixed frame parts is located in one unit frame region formed by the drive frames and auxiliary drive frames, and the fixed frames are separately and electrically connected for each of the fixed frame parts.
It is preferable that ends of the spring members of the first and second spring parts are formed by spring connecting elements, and each of the spring holding members is located between neighboring spring members to connect the same and has a length shorter than the spring members, and one side of the second spring parts is connected to a spring support fixed to the substrate.
It is preferable that each of the spring holding members of the first and second spring parts comprises a plurality of connecting plates arranged in a zigzag pattern at a predetermined angle with respect to the spring members to connect neighboring spring members.